Glaucoma

What Is Glaucoma? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Sara Altshul
By Medically Reviewed by 
Reviewed:
Medically Reviewed

Glaucoma is an often painless but serious eye condition that causes damage to your optic nerve.

This nerve connects your eye to your brain, allowing the incoming visual information to be processed by the brain, which then identifies what you’re seeing.

The condition can cause blindness. Indeed, glaucoma is the second leading cause of blindness in the world.

Signs and Symptoms of Glaucoma

Although glaucoma usually doesn’t cause obvious symptoms at first, some early warning signs may indicate its onset.

These signs may include changes in your vision, such as blurring and sensitivity to light, headaches, and pain in or around the eyes.

Symptoms may come and go or worsen over time.

Learn More About Signs and Symptoms of Glaucoma

Causes and Risk Factors of Glaucoma

Researchers don’t fully understand how glaucoma occurs.

One known cause is the optic nerve becoming compressed because of high pressure within the eye. Another cause can be reduced blood flow within the optic nerve.

But even people with normal eye pressure can develop glaucoma. In addition to high eye pressure, high blood pressure can also lead to optic nerve damage.

Unfortunately, glaucoma has no obvious warning signs and causes no pain. Once damage to your eyesight has occurred, it cannot be reversed.

With an early diagnosis, there are treatments available that can slow the progression of the disease and prevent vision loss.

The top risk factor for glaucoma is having high pressure within your eye.

Other important risk factors include:

  • Being age 40 or older
  • African, Hispanic, or Asian heritage
  • Thin corneas (the clear layer at the front of the eye)
  • Family history of glaucoma
  • Farsightedness or nearsightedness
  • Previous eye injuries
  • Steroid medication use
  • Certain conditions, such as diabetes, migraines, hypertension, or poor blood circulation.
People with more than one of these factors are at a higher risk of developing glaucoma.

What Is Intraocular Pressure?

Within healthy eyes, there’s a clear fluid called aqueous humor that circulates to nourish the eye and its various parts. This fluid normally drains out of the eye.

When drainage is slowed, pressure within the eye (called intraocular pressure) can build up and harm the optic nerve by compressing it.

The optic nerve is vital to your ability to see. It carries signals from the retina in the eye to the brain.

When the optic nerve’s fibers are damaged, blind spots can develop in your field of vision.

Types of Glaucoma

There are several different kinds of glaucoma.

 They include:

Primary Open-Angle Glaucoma

This is the most common form of glaucoma.

It occurs when the eye’s fluid passes too slowly through the open drainage “angle” where the eye’s cornea and iris meet.

The first sign of a problem with this type of glaucoma is usually the loss of your peripheral (side) vision.

You may compensate, without knowing it, by turning your head to the side to see things. You may not realize you’re losing your vision until the loss is severe.

Low-Tension or Normal-Tension Glaucoma

In this form of glaucoma, optic nerve damage occurs even though your eye pressure is not very high. It’s unclear why the damage occurs.

Angle-Closure Glaucoma

Formerly called narrow-angle glaucoma, this urgent medical emergency occurs when the drainage angle closes because it’s blocked by part of the iris.

Eye pressure builds suddenly when fluid can’t drain from your eye.

With this type of glaucoma, you’ll experience severe pain and nausea. Your eye will redden and your vision will blur.

It’s very important to seek emergency treatment immediately at a hospital or clinic. Without treatment, you could lose sight in the affected eye.

In most cases, laser surgery and drugs can clear the blockage, lower the eye’s pressure, and restore vision.

Congenital (Childhood) Glaucoma

Babies can be born with a defective angle in the eye that doesn’t allow fluid to drain properly.

The symptoms of congenital glaucoma are usually quite noticeable.

Children with the condition may have a cloudy eye, be very sensitive to light, or produce an excess of tears.

Your child’s doctor will likely recommend a surgical procedure to correct the problem.

The procedure is considered safe and effective. When done early in life, it offers children an excellent chance of having good vision.

Other types of glaucoma include:

Pigmentary Glaucoma

This relatively rare type of glaucoma is a complication of a condition known as pigment dispersion syndrome. It occurs when pigment granules at the back of the iris flake off into the fluid in the eye. If they clog the eye’s drainage canals, it can lead to increased eye pressure and optic nerve damage. About 30 percent of cases of pigment dispersion syndrome lead to pigmentary glaucoma.

Traumatic Glaucoma

Injury to the eye that may be caused by blunt trauma to the head or flying debris can lead to glaucoma.

When bleeding in the eye occurs, the eye’s drainage system can become clogged and lead to increased eye pressure.

Traumatic glaucoma most commonly occurs when the ciliary body, which produces eye fluid, is torn.

Iridocorneal Endothelial Syndrome (ICE)

ICE occurs when cells on the back of the cornea spread over drainage tissue in the eye. This leads to blockage of the drainage canals and eye pressure buildup.

Uveitic Glaucoma

Uveitis is an inflammation of the uvea, or the middle layer of the eye that’s located under the white of the eye. The inflammation can obstruct fluid outflow from the eye. Up to 20 percent of uveitis patients develop glaucoma, either due to inflammation or due to use of steroids to treat the inflammation.

How Is Glaucoma Diagnosed?

An eye examination is the best way to detect glaucoma. The American Academy of Ophthalmology (AAO) recommends that everyone get a baseline eye exam by age 40 — or sooner if you have risk factors for eye disease, such as high blood pressure or diabetes.

The AAO recommends that adults ages 40 to 54, without risk factors, should get a comprehensive eye evaluation every two to four years. Individuals without risk factors ages 55 to 65 should be examined by an ophthalmologist every one to three years. And those over 65 should have an exam performed every one to two years. If you have risk factors, you may need more frequent examinations.

There are several tests used to detect glaucoma, including tonometry, which measures the pressure inside the eye;

gonioscopy, which is an examination of the eye’s drainage angle (where the cornea and iris meet);

and perimetry, which measures the scope of central and peripheral vision.

Learn More About How Glaucoma Is Diagnosed: Tests and Screening

Prognosis of Glaucoma

The prognosis of glaucoma depends on what type of glaucoma it is and how soon it is diagnosed and managed, says Annapurna Singh, MD, an ophthalmologist at the Cleveland Clinic.

“If a baby or child is diagnosed early with congenital glaucoma and gets treatment, he or she can have a good quality of life,” says Dr. Singh.

For someone with open-angle glaucoma in midlife or later, the sooner they are diagnosed and treated, the lower the chances they’ll go blind as a result, she says.

If chronic glaucoma is left untreated, it can result in permanent damage.

In the case of acute glaucoma, if it’s treated early, the vision in the affected eye may return to what it was before the episode. If acute glaucoma is not diagnosed or treated, it can result in blindness in the affected eye in two days or even sooner.

“Essentially, the sooner the diagnosis and treatment, the better the prognosis,” says Singh.

Duration of Glaucoma

If a person develops glaucoma, they will have it for the rest of their lives. Timely diagnosis and treatment can prevent loss of vision.

Even after glaucoma is treated with medicine or by surgery, the patient will need to be followed for the rest of their lives, says Singh. “That is to make sure they don’t get another form of glaucoma or in case their treatment was not enough, and they now need some additional medical therapy to keep that pressure under control,” she says.

Treatment and Medication Options for Glaucoma

There is no cure for glaucoma. Nerve damage and vision loss caused by the disease cannot be reversed.

But there are treatments available that can slow the progression of the disease and prevent loss of vision, especially if it is caught in the early stages.

The goal of any treatment is to reduce the pressure in the eye. Treatment options include medication (eye drops or oral drugs), laser therapy, and conventional surgery, either individually or in combination.

Surgical options include laser surgery (laser trabeculoplasty) and conventional surgery (trabeculectomy).

Medication Options

If you are diagnosed with glaucoma, your doctor will most likely prescribe eye drops as the first line of treatment. These eye drops, which fall into several categories of drugs, can lower eye pressure by helping fluids drain or by reducing the amount of fluid produced by the eye.

Alternative and Complementary Therapies

There really hasn’t been much research on alternative and complementary therapies, says Singh.

The results of those nonstandard treatments have had “little to no effect,” according to the Glaucoma Research Foundation.

No vitamin supplement has been found to have an effect on intraocular pressure (IOP) or the visual field.

Ginkgo biloba is an antioxidant herb. One study found that it “appears to improve visual fields in some” people with chronic open-angle glaucoma, but there were questions about the strength of the research.

Marijuana has been shown to produce a temporary decrease in IOP, but the decrease lasts only for a short period. In order to be effective, it needs to be taken many times a day, which could lead to potential risks, including emphysema and lung cancer.

Learn More About Treatment for Glaucoma: Medication, Alternative and Complementary Therapies, Surgery Options, and More

Prevention of Glaucoma

There’s really no way to prevent glaucoma, says Singh. “Essentially, prevention is seeing your eye doctor on a regular basis,” she says.

Regular eye exams include tonometry, dilated exams of the optic nerve, and screening tests of the visual field, and these visits are recommended for all people age 40 and over, especially Black Americans and people with a family history of glaucoma.

It’s very important to have the nerves of the eye examined along with checking the pressure (tonometry), says Singh. “Sometimes if the eye doctor is only checking the pressure, glaucoma can be missed up to 50 percent of the time. It’s important to see an eye doctor who is actually examining the nerves,” she says.

There is evidence to suggest that exercise may play a role in glaucoma prevention. A study suggested that people who got the recommended amount of physical activity (150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week, or an equivalent combination of both) could significantly reduce the risk of developing glaucoma.

Complications of Glaucoma

If glaucoma goes untreated, it can cause significant vision loss that can’t be restored. If it goes untreated long enough, it can lead to vision loss in both eyes and may even lead to blindness.

Blindness as a result of glaucoma is a rare occurrence, says Singh. It happens in approximately 10 percent of people who are diagnosed with glaucoma.

As with any surgery, there can be risks from glaucoma surgery. These complications can include vision loss that doesn’t go away, bleeding, infection, low eye pressure, scarring, and cataract formation.

Research and Statistics: Who Has Glaucoma?

“You can be born with glaucoma or you can get it in your seventies, eighties, and nineties,” says Singh.

More than three million Americans have glaucoma, but only half of them know they have it.

The prevalence of glaucoma increases as people get older. In 2014, glaucoma affected about 1.9 percent of people over 40.

Black Americans have the highest prevalence rate, at 3.4 percent. For white Americans, it is 2.1 percent, and for Hispanic Americans, 1.5 percent.

Because women have a longer life expectancy, they are more likely than men to develop an age-related eye disease such as glaucoma. About 6 in 10 U.S. glaucoma cases are in women.

Black Americans, Hispanic Americans, and Glaucoma

Black Americans and Glaucoma

Glaucoma occurs about 5 times more often in Black Americans than in other groups, and blindness from the disease is 6 times more common. There are many factors that contribute to this disparity, says Singh.

“Genetics appears to have a role, as well as things such as access to healthcare or lack of insurance,” she says.

Private health insurance appears to play a large part in glaucoma testing, which is necessary for timely diagnosis and treatment. One study found that Black Americans with Medicaid insurance had almost 3 times the chance of not receiving any glaucoma testing compared with those with private health insurance.

The authors concluded that disparities in testing were observed for people with Medicaid insurance versus commercial insurance across all races and ethnicities but were most notable for Black Americans.

According to U.S. Census estimates from 2018, the uninsured rate was 17.8 percent among Hispanic Americans and 9.7 percent for Black Americans, compared with 5.4 percent among white Americans. The percentage of people who had private insurance was 49.6 percent for Hispanic Americans, 55.4 percent for Black Americans, and 74.8 percent for white Americans.

Hispanic Americans and Glaucoma

The Los Angeles Latino Eye Study (LALES) reported an overall prevalence of open-angle glaucoma among Hispanics at nearly 5 percent — similar to what has been reported for Black Americans.

It’s estimated that by 2050, half the people living in the United States with glaucoma will be Hispanic or Latino. Lack of access to healthcare and health insurance is a big part of the issue. Hispanic Americans are less likely to have had an eye exam or have access to eye health and eye care services, according to the CDC.

Related Conditions and Causes of Glaucoma

Glaucoma shares some similarities with other common eye conditions, such as cataracts and dry eye. But these are distinct conditions with different underlying causes and treatment options.

Cataracts

Like glaucoma, a cataract is a serious degenerative eye disease that can lead to loss of vision. In fact, cataracts are the leading cause of vision loss in the United States. An estimated 20.5 million Americans ages 40 and older have the disease.

Cataracts develop when proteins in the lens of the eye (the clear part of the eye located behind the iris and pupil) clump together. The result is a clouding of the lens.

One of the possible complications of glaucoma surgery is the development of cataracts.

Cataracts are diagnosed with a comprehensive eye exam, using some of the same tests that are performed to diagnose glaucoma. Unlike glaucoma, which can often be managed with medication, the only way to treat cataracts is with surgery.

Learn More About Cataracts

Dry Eye

Dry eye is a condition caused by the production of a low quantity or quality of tears, resulting in eye irritation and vision problems.

Dry eye and glaucoma often coexist; an estimated 40 to 50 percent of glaucoma patients also have dry eye syndrome.

Eye drops prescribed to treat glaucoma can cause dry eye symptoms. If your eye drops cause redness and stinging, your doctor may recommend a preservative-free alternative.

Learn More About Dry Eye

Resources We Love

American Academy of Ophthalmology

The mission of the American Academy of Ophthalmology is to protect sight and empower lives by advocating for patients, as well as educating the public and eye health professionals.

Glaucoma Research Foundation

This national nonprofit organization is dedicated to finding a cure for glaucoma. It provides information, tips on eye care, and updates on the latest research.

American Glaucoma Society

This professional organization provides clinical and scientific evidence for both patients and healthcare professionals. A patient portal contains resources on finding an eye doctor, education on glaucoma and answers to FAQs.

National Eye Institute

The National Eye Institute was established by congress over 50 years ago to protect and prolong the vision of the American people. This organization provides education and funds research in eye health.

Additional reporting by Becky Upham.

Editorial Sources and Fact-Checking

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